Field of the Invention
Exemplary embodiments of the present invention relate to a method and apparatus for controlling power generation load based on a coasting operation; and, particularly, to a method and apparatus for controlling power generation load based on a coasting operation which allow to efficiently collect inertial energy and improve fuel efficiency in such a way to differently control power generation load based on a coasting operation and a history of the coasting operation.
Description of Related Art
To improve fuel efficiency in preparation for rising oil price, it needs to efficiently control power generation load of a generator based on the running condition of a vehicle.
For example, as illustrated in FIG. 1, a generator 12 driven by an engine 11 allows to generate power while maintaining a set voltage through a regulator 12a, and the engine 11 and the generator 12 are configured to transfer information of the engine 11 and the generator 12 to an ECU 13 and are controlled by the ECU 13. The ECU 13 receives information through a sensor 16 with respect to a battery 14 charged by the generator 12 and controls the engine 11, the generator 12 and a cooling fan 17 and supplies electric power from the battery 14 to electric loads 15 of a vehicle.
The vehicle with the above power generation system increases the load of the generator in the deceleration mode wherein fuel is less consumed and stores in the battery, and in the mode wherein fuel is more used, supplies to electric loads of the vehicle using the energy stored in the battery, thus improving fuel efficiency by reducing the generation of power.
In the conventional power generation control, if fuel cut occurs in the deceleration mode, the kinetic energy of the vehicle, which was running in the inertial mode by maximally increasing the voltage from the generator, is converted into electric energy. At this time, in the fuel cut operation mode wherein the vehicle runs without any brake operation, the vehicle will decelerate because of the friction force of the engine.
Meanwhile, if the power generation voltage of the generator is increased during the fuel cut operation wherein the vehicle runs without any operation of the brake, the friction force of the engine further increases as high as the load of power generation, thus reducing the duel cut operation time of the engine.
The above-described control may not be an effective way as compared to the control method wherein fuel efficiency has priority, for enhancing fuel efficiency in such a way to maintaining the fuel cut operation time as long as possible.
In the conventional art proposed to resolve the above-mentioned problems, when the vehicle starts a fuel cut operation, the power generation load of the generator is increased if deceleration is high given the deceleration of the vehicle, and in other occasions, the vehicle is controlled by maintaining long the fuel cut operation time while keeping low the power generation load. However, since the coasting operation section in the conventional art is not considered an energy recovery section, the vehicle has been controlled in the same way as the conventional control during the coasting operation of the vehicle. Here, the coasting operation of the vehicle represents that if a driver steps off an accelerator pedal at a prejudged vehicle speed so as to improve fuel efficiency, the vehicle is forced to run in the inertial mode by disconnecting the transfer of the driving force to the engine and the transmission. In the conventional vehicle control, if the load of the generator increases in the coasting operation section, the coasting running section may become short, which may have bad effect on the improvement of the fuel efficiency.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.